Which one of these equations represents the reaction of a weak acid with a strong base?

a. h + (aq) + oh - (aq) → h2o (aq)

b. h + (aq) + ch3nh2 (aq) → ch3nh3 + (aq)

c. oh - (aq) + hcn (aq) → h2o (aq) + cn - (aq)

d. hcn (aq) + ch3nh2 (aq) → ch3nh3 + (aq) + cn - (aq) ?

Answer:-

c. OH - (aq) + HCNaq) → H2O (aq) + CN - (aq)

Explanation:-

A strong base is one which is fully dissociated in aqueous solution. So if we are looking for a strong base we should be looking for OH - (aq).

Similarly a strong acid is one which is fully dissociated in aqueous solution. So if we are looking for a strong acid we should be looking for H + (aq).

The questions is asking for a weak acid and a strong base. So our answer should have a OH - but not a H + on the left side of the correct answer.

So our only possible answer is option C.